A relative pressure sensor of the field of the invention includes a pressure measuring transducer, wherein the pressure measuring transducer has a measuring membrane and a platform, wherein, between the measuring membrane and the platform, a reference pressure chamber is formed, a support body, wherein the platform is connected with the support body by means of a pressure-bearing adhesion, wherein a reference pressure path extends through the platform and the support body, in order to introduce reference pressure into the reference pressure chamber, a sensor outer body, in which a transducer chamber is formed, wherein the transducer chamber has a first opening and a second opening, wherein the pressure measuring transducer is brought into the transducer chamber through the first opening, and is held in the transducer chamber by means of the support body, wherein the support body pressure-tightly seals the first opening, and wherein a side of the measuring membrane facing away from the reference pressure chamber is contactable with the media pressure via the second opening.
In the case of the relative pressure sensors of the field of the invention, the problem arises that the pressure-bearing adhesion is moisture sensitive. This leads to mechanical stresses in the pressure measuring transducer, which ultimately cause measurement errors. In this regard, German patent application 102008043175 describes approaches to change the topology of the pressure-bearing adhesion, through which, in the case of the pressure sensor of the invention, the reference pressure path extends, in such a manner that the pressure-bearing adhesion is protected from the reference air by a moisture barrier.
Although these approaches effect an improvement, they are not fundamental solutions, since these types of barriers—for example, a silicone layer on the adhesion or a rubber hose between the adhesion and reference air path—are not hermetically sealed, and thus the ratio of effort required to improvement achieved still leaves a good deal to be desired.
European patent application EP 1065488A1 discloses a capacitive, ceramic, relative pressure sensor including: A gas-filled measuring chamber, which is sealed with a ceramic measuring membrane, on whose outside pressure to be measured acts during operation; a gas filled, compressible, resilient bellows, on which a reference pressure acts externally during operation, and whose internal volume depends on its reference pressure, and which, for matching an internal pressure reigning in the measuring chamber to the reference pressure, communicates with the measuring chamber; and a transducer for conversion of a pressure-dependent deformation of the measuring membrane into an electrical, measured variable. In the detailed description, it is disclosed that the resilient bellows can especially have metal membranes, for example, wave membranes or resilient plastic membranes, wherein, here, the elasticity clearly plays a large role. Thus, elasticity means the presence of a return force, which absolutely unavoidably leads to a corrupted reference pressure, and therewith to measurement error.